Organic electroluminescence devices have advantageous features such as self emission and high-speed response and are expected for the application to flat panel displays. In particular, since such organic electroluminescence devices were reported that have a dual-layer structure (lamination type) in which a hole-transporting organic thin film (hole transport layer) is laminated on an electron-transporting organic thin film (electron transport layer), organic electroluminescence devices have been attracting attention as a large-area light-emitting device that emits light at a low voltage of 10 V or lower. The organic electroluminescence devices of lamination type have a basic structure of anode/hole transport layer/emission layer/electron transport layer/cathode.
In order to improve the surface uniformity of such organic electroluminescence devices the following production methods have been proposed for example: (i) a production method where a mixture of polyethylenedioxythiophene (PEDOT)/polystyrene sulfonic acid (PSS) is leveled under high-temperature/high-humidity environments to form a hole transport layer (see, for example, PTL 1); (ii) a production method where heat treatment in a mode of being heated from the rear surface is performed at a temperature which falls within the range of −30° C. to +30° C. of the glass transition temperature of a light-emitting layer and which does not exceed the decomposition temperatures of organic compounds forming the light-emitting layer, a dicarbazole derivative (CBP) is used as a host material, and toluene is used as a solvent (see, for example, PTL 2); and (iii) a production method where an organic light-emitting medium layer is heated upon drying to a temperature equal to or higher than the boiling point of an organic solvent contained in a functional ink; i.e., around the glass transition temperature (Tg) (see, for example, PTL 3).
However, the organic electroluminescence devices produced by these production methods have a problem in that the surface uniformity of the light-emitting layer is not sufficient.
Therefore, at present, keen demand has arisen for development of a production method for an organic electroluminescence device the light-emitting layer of which has sufficient surface uniformity.